One of the most important issues in conventional medical treatment of peritoneal dialysis has been how to correctly determine the peritoneal dialysis state and the peritoneal permeability of peritoneal dialysis patients so as to evaluate the peritoneal function and determine the optimum dialysis conditions. For example, with Continuous Ambulatory Peritoneal Dialysis (CAPD), which is a so-called chronic peritoneal dialysis treatment that was proposed in the 1970s, approximately two liters of peritoneal dialysis fluid is retained within the abdominal cavity for five to six hours, and is exchanged from four to six times daily. Also, to maintain constancy within the patient's body, the dialysis function and water removal function (hereinafter, collectively referred to as “peritoneal function”) of the patient's peritoneum is evaluated, and the most suitable dialysis fluid exchange schedule (hereinafter, referred to as “dose”) based on that evaluation is set.
However, during the 1970s, which is when CAPD was proposed, very little was known of the characteristics of peritoneal function and the change over time in peritoneal function over the course of peritoneal dialysis, and thus there was no established testing method for appropriately evaluating peritoneal function, and the dose was set based on physician experience and judgment.
By the 1980s, as the number of clinical cases increased, it became clear that peritoneal function differed for each patient, and methods for testing peritoneal function involving qualitative evaluation of dialysis function and water removal function were proposed. Peritoneal Equilibrium Test (hereinafter, also referred to as “PET”) is one of the most frequently used qualitative evaluation methods. With PET, peritoneal function is divided into four categories, these being good, moderately good, moderately poor, and poor, and a general dose pattern that is considered appropriate is proposed for each category.
By the 1990s, it was shown that there are limitations to the patients for which qualitative evaluation methods may be adopted, and quantitative evaluation methods that take patient body type into account were proposed. The quantitative evaluation method uses creatinine clearance, which is one index for the dialysis amount of chronic peritoneal dialysis patients, urea Kt/V, and statistical results on survival rates, as criteria. The dose that satisfies the quantitative criteria of these two parameters with respect to survival rate is judged to be the optimum dosage. By using the above qualitative evaluation method and this quantitative evaluation in tandem, it became possible to determine the optimum dose pattern and dose.
The use of these two evaluation methods in tandem, however, at most results in only an evaluation of the suitability of a dose at various points. Consequently, the setting of the dose was performed by trial and error, and there was the problem that the physician had only his experience to rely on when setting a dose.
Accordingly, a computer simulation that builds a mathematical model of chronic peritoneal dialysis methods and proposes the most suitable dose based on analysis of the speed at which the peritoneum moves substances was proposed. Using computer simulation made it possible to propose a dose suited for the peritoneal function of the patient by adopting both the dose pattern proposed by qualitative evaluation and the criteria indicated by quantitative evaluation.
However, there was no effective and economical clinical data collection protocol (testing method) for collecting the data necessary for this analysis. Although numerous clinical data collection protocols (testing methods) for implementing computer simulation have been proposed, each of the methods takes the body's circadian rhythm into consideration and measures the material balance of monitored solutes (such as urine toxins) and the uptake and release of water over a 24-hour period.
FIG. 1 shows an example of the procedure of a conventional method for testing peritoneal function. The horizontal axis shows the time elapsed from the start of testing. “Fluid infusion” and “fluid drain” in accordance with the passage of time are shown. Also, the timing of a body weight measurement 11, a blood draw 12, a urine storage 13, and a urine test 14 are shown in relation to “fluid infusion” and “fluid drain.”
As shown in FIG. 1, to detect the material balance of monitored solutes (such as urine toxins) and the uptake and release of water over a 24-hour period, first, infusion of a low osmotic pressure fluid (360 (units are m0sm/kg-solvent; same below)), which is a dialysis fluid having a low osmotic pressure, is begun in the evening (22:30) two days prior to the day on which testing is finished. The next morning the fluid is drained and a first blood sample 12 (8:00) is taken.
Next, a body weight measurement 11 is performed, and then a medium osmotic fluid (400), which is a dialysis fluid having a high osmotic pressure, is infused, and for the peritoneal equilibrium test (PET), the fluid is drained, some is sampled, and then is returned two times at predetermined time intervals, after which the fluid is finally drained. It should be noted that in general PET is performed using a medium osmotic pressure fluid (400). Also, PET is a test that should be performed in the hospital, and the second blood sample 12 is generally taken while the patient is in the hospital. After that the dialysis fluid is infused and drained, and when the final fluid drain is complete (8:00), a third blood sample 12 is taken and a urine test 14 is performed.
In this testing procedure, the patient was forced to stay in the hospital because it was necessary to take a blood sample and perform a PET. In other words, in the above test, several blood samples are taken during a 24-hour period. It was therefore frequently necessary to admit patients to the hospital, depending on their living environment, and this was a problem because it imposed time constraints on patients and left them mentally fatigued.
There was also the problem that the large number of tests placed a large time and work burden on the patient and medical staff, and in spite of this, it was difficult to gather data that accurately reflected the normal daily condition of the patient.